CNG cylinders pulled after blast

All 375 imported cylinders of compressed natural gas (CNG) from the shipment that contained a tank that exploded last week have been removed from the market pending a safety review. Siam Ratchathani Co, the company that imported the cylinders in April, had agreed to the withdrawal, said Norkhun Sitthipong, the deputy permanent secretary of the Energy Ministry. The company would offer free replacement CNG kits to any customers who had purchased the units, he added. The explosion took place on Friday at a PTT service station in Samut Prakan, where a privately owned bus was being refuelled. A pump attendant was injured and seven vehicles damaged. Most of the 145-litre-cylinders with serial numbers from 54187 to 545562 had been installed in trucks and buses and a total of 90 cylinders were in the process of being installed in garages. The importer told the ministry that the 375 cylinders had been manufactured by Fine Tech Co of South Korea with steel from China. Fine Tech executives flew to Thailand shortly after Friday's incident and offered to recall the products and pay compensation to clients itself. Mr Norkhun said the cylinders had received ISO 11439 international certification and had also been installed by certified garages and technicians. ''The material of these tanks might be the main root cause,'' a spokesman for the importer said. ''Normally a CNG cylinder needs a special grade of steel, which should have light weight but be very strong to withstand high pressure of at least 200 bars.'' Representatives of Siam Ratchathani, Fine Tech, PTT and Energy Ministry officials are all co-operating in an investigation to determine the cause and prevent a repeat incident.Mr Norkhun said that while the cylinder was certified, it might have been positioned improperly in the bus during installation. Kasetsart University experts have also agreed to conduct a safety test of the burst cylinder with the results expected within two weeks. PTT has been asked not to refill any vehicles containing cylinders from the affected shipment, said Sirisak Wittaya-udon, the deputy director-general of the Department of Energy Business. More than 100,000 CNG cylinders have been installed in local vehicles and Friday's accident was only the second of its kind, he added.
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